He came in second in the New Hampshire primary. He has raised more money than any Republican candidate except for Mitt Romney. His campaign rallies still draw thousands of fervent supporters, far more than any of his rivals’. College students give him rock-star treatment, and he is planning rallies at 30 campuses over two months.

But turn those strengths into a candidacy with a real shot at the Republican presidential nomination?

It never happened. His strategists are searching for answers, and one may be that many who turned up for his rallies were less eager to take part in Republican primaries or argue Mr. Paul’s case at Republican caucuses.

Even Mr. Paul cannot entirely explain why the passion he generated, especially among young people and those his campaign identified as motivated supporters, did not translate into more votes.

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Mr. Paul preparing to go on Jay Leno’s show.Credit
Michal Czerwonka for The New York Times

“I don’t have a full answer for that,” says Mr. Paul, who says he believes ballot irregularities have chipped into his numbers in some places. He adds, “I think there’s some problem with always making sure this energy is translated into getting to the polls.”

Though the campaign says it still has some tricks up its sleeve, it now faces a hurdle just to place Mr. Paul’s name in contention for the nomination: a Republican convention rule requiring a candidate to have the greatest number of delegates from each of at least five states.

Mr. Paul said in an interview last week that he was “real satisfied” with the campaign. “You could always argue you wish you could do better, but we could have done worse, too.” He is already far ahead of his 2008 performance, including second-place finishes in seven states this year. But he remains in fourth place over all, with one-eleventh the delegates of the front-runner, Mitt Romney, according to an estimate by The Associated Press.

What Mr. Paul may have by the end of the nominating race is a valuable collection of delegates. So he could still play an important role at the August convention in Tampa, Fla. — especially if Mr. Romney fails to obtain 1,144 delegates to secure nomination on the first ballot, which is the hope, albeit perhaps fading, of Rick Santorum and Newt Gingrich.

Mr. Paul has so far earned 50 delegates, according to the A.P. tally, and the campaign hopes efforts to obtain more delegates at state party conventions will mean he will have 150 to 350 delegates bound to him for the convention. Aides also believe he will ultimately win enough delegates to satisfy the five-state nominating threshold, as supporters pack state party gatherings in coming months and battle to select national delegates loyal to Mr. Paul in proportions greater than the percentage of votes he received.

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Young fans of Mr. Paul in Henderson, Nev.Credit
Monica Almeida/The New York Times

“There is a lot of stuff in motion,” he says. “This is what people don’t know about yet.”

Whether he will use those delegates to help Mr. Romney is an open question. Mr. Paul demurs when pressed on whether he would help Mr. Romney, a former Massachusetts governor, should he fail to clinch the nomination on the first try, saying, “I haven’t thought much about that.”

While he has a personal affinity for Mr. Romney (though he can be scathing about his friend’s politics), Mr. Paul has tart words for Mr. Santorum and Mr. Gingrich, even scoffing at the idea the two men could ever agree to cooperate to try to defeat Mr. Romney.

“I think their egos are too big,” Mr. Paul said. “They’ll fight over who’s going to be top dog.”

He has, however, taken comfort in their movement toward his point of view on the war in Afghanistan. Mr. Gingrich has recently suggested pulling out of Afghanistan, and Mr. Santorum has said one option would be withdrawing faster than the Obama administration’s 2014 timeline.

“They know what the politics of it is,” Mr. Paul says. “That’s what disgusts me. Why don’t they take a stand and save some lives?”

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Mr. Paul at an event in Chanhassen, Minn., early last month. His rallies continue to draw thousands of fervent supporters.Credit
Ben Garvin for The New York Times

The huge gap between Mr. Paul’s noninterventionist foreign policy and the hawkishness of other Republicans is one reason, in Mr. Paul’s estimate, that “probably half” of his backers are not comfortable within the Republican Party. That seems particularly true of many college students, the driving force behind his largest rallies.

And some of his supporters may be more motivated to attend rallies than to vote for him: A Feb. 27 event at Michigan State University drew 4,000 people. But at polling places the next day, Mr. Paul finished third — with 3,128 votes — in Ingham County, where the campus is. Mr. Romney got more than three times as many votes.

This phenomenon is not limited to campuses. Paul aides have made a case study of Nevada, which they use to help instruct staff members in states that have not yet voted, according to one senior adviser who refused to be identified because he was discussing internal campaign strategy.

The campaign had high hopes for the state, where the 76-year-old Mr. Paul had a powerful organization and a message that dovetailed with Nevada’s libertarian streak, even earning the support of its most flamboyant brothel owner. (While Mr. Paul embraces civil liberties, he is personally modest and decorous, so much so that while awaiting a recent appearance here on “The Tonight Show,” he seemed embarrassed listening in his dressing room to a few monologue jokes told by the host Jay Leno — at the expense of Mr. Santorum — about masturbation.)

In Nevada, the campaign identified 23,000 people motivated to vote for Mr. Paul and flooded them with e-mails, postcards and calls, according to the senior aide. But Mr. Paul received 6,175 votes statewide. Even Nye County — a libertarian stronghold where Mr. Paul won almost half the vote — was a disappointment: The number of votes he got, 454, was perhaps only a hundred or so more than the number of people who attended a rally there a few days earlier at which his state chairman had announced 800 new voters registered in the county.

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One of Mr. Paul's supporters in Phoenix.Credit
Eric Thayer for The New York Times

“I guess our failing was in expressing the urgency of the need to get out there,” the Paul aide said.

Jesse Benton, Mr. Paul’s national chairman, says the campaign has no regrets. “If you had told us at the start of the race where we would be now, with no candidate having a majority of delegates, and with a shot at a brokered convention, we would have taken it,” he said.

The campaign is now trying to build up a few million dollars in cash for primaries in California and Texas. It raised $7.8 million during the first two months of the year, down from the pace late last year but a robust number for a candidate widely seen as having little or no chance at the nomination. While the campaign has focused on Internet donations and mail and telephone solicitations, it expects to conduct more traditional fund-raising in coming months, including a $2,500-a-plate event May 1 hosted by Mark Spitznagel, a hedge fund manager whose bearish bets have earned him a fortune.

Last Tuesday, before Mr. Leno’s show, Mr. Paul spoke at a fund-raiser at a Marriott here in front of 160 supporters who paid $350 each. He spent an hour meeting them and taking pictures, with each donor getting 15 to 20 seconds with him. There were wealthy men with clipped accents and trim, carefully tailored suits, and pudgy college-age kids in sweat pants and jeans. Some brought yard signs or booklet-size copies of the Constitution for him to sign.

One woman, in a form-fitting dress that made plain how pregnant she was, told Mr. Paul, who worked decades as an obstetrician, “I wish you could deliver my baby.”

A version of this article appears in print on March 28, 2012, on page A12 of the New York edition with the headline: Strength And Weakness In Campaign Of Ron Paul. Order Reprints|Today's Paper|Subscribe